1. Field of the Invention
The present invention relates to insertion devices used in medical procedures and methods of use of same.
2. Description of the Related Art
In the industrialized world, trauma is the leading cause of death in males under the age of forty. In the United States, chest injuries are responsible for one-fourth of all trauma deaths. Many of these fatalities could be prevented by early recognition of the injury followed by prompt management.
The lungs are surrounded by a pleural sac that consists of two membranes, the visceral and parietal pleurae. The parietal pleura lines the thoracic wall, and the visceral pleura surrounds the lung. The pleural space is a potential space between these two layers of pleurae. It contains a thin layer of serous pleural fluid that provides lubrication for the pleurae and allows the layers of pleurae to smoothly slide over each other during respiration.
Pneumothorax (air in the pleural space) and hemothorax (blood in the pleural space) are commonly occurring chest injuries. Pneumothorax and hemothorax are common consequences of chest trauma, second in frequency only to simple rib fractures, soft tissue injuries of the chest wall, and lung contusion. More importantly, pneumothorax and hemothorax are potentially lethal unless treated promptly. Common causes of pneumothorax and hemothorax include penetrating injuries (e.g., gunshot and stab wounds or injuries occurring as the result of a surgical procedure) and blunt injuries (e.g., from direct blows, crushing injuries, blasts, or falls). Pneumothorax may also occur as a result of the use of positive end-expiratory pressure (PEEP) in connection with mechanical ventilation procedures, or spontaneously as a result of emphysematous blebs (air spaces that may occur in the lung as a result of emphysema).
Normally, the pressure in the pleural space is much lower than the atmospheric pressure. Following trauma, air may enter the pleural space in several ways, e.g., through a communication between the pleural space and the outside air, or a leak from disrupted alveoli, bronchi or ruptured esophagus. The entry of air into the pleural space (pneuomthorax) results in an increase in the pressure in the pleural space. The increase of pressure in the pleural space compresses the lung, which can cause a potentially fatal condition known as a collapsed lung.
Eliminating pneumothorax requires prompt decompression of the pleural space, usually accomplished by the insertion of a chest tube and evacuation of the air. Similar procedures are followed during the occurrence of a hemothorax to remove blood from the pleural space. More specifically, in order to decompress the pleural cavity, a chest tube is inserted through the appropriate intercostal space, which is the area between adjacent ribs. Typically the intercostal space is approximately 1-2 cm in size. However, there are significant individual differences depending on the size of the individual, and the phase of the respiratory cycle (the intercostal spaces widen during normal inspiration). Furthermore, there are substantial regional size differences, e.g., the intercostal spaces are deeper anteriorly than posteriorly, and deeper between the superior than the inferior ribs. The lateral part of the intercostal space is the widest zone of the intercostal space (i.e., at the anterior axillary line). In addition to the differences in size from one individual to the next, the composition of the chest wall itself can vary from person to person and also differs based on the gender of the patient. The male chest wall is composed of a greater percentage of muscle tissue than the female chest wall. On the other hand, the female chest wall is composed of a greater percentage of adipose tissue than the male chest wall. Each intercostal space contains three muscles: the innermost intercostal muscles, the internal intercostal muscles, and the external intercostal muscles. In addition, each intercostal space contains a neurovascular bundle (intercostal vein, artery and nerve) that runs below the ribs. Further, the chest wall is covered superficially by muscles, connective tissue and skin. For example, the chest wall, in the fifth intercostal space, anterior axillary line is covered externally by the serratus anterior muscle. The chest wall thickness (CWT) is defined as the length from the thoracic epidermal surface to the parietal pleural lining of the lung. As with the intercostal spaces and chest wall composition, there can be a great variation in chest wall thickness from individual to individual and from location to location in the same individual. For example, studies have shown that the mean male CWT increases by 70% laterally, and by 30% posteriorly, as compared with the anterior chest wall. The mean female CWT increases by 86% laterally, and by 85% posteriorly, as compared with the anterior chest wall. Further, the position of the patient can also affect the CWT; the CWT is a few millimeters less when the patient is in a reclined position (torso 45 degrees from horizontal) as compared with the same measurement taken when the patient is in the supine position.
The above-described physical differences between individuals must be considered when inserting a chest tube into a patient. There are several other key factors that come into play when inserting chest tubes, including insertion location, penetration angle, and depth. The primary goals of the tube insertion are to effectively evacuate the unwanted air/blood from the pleural space while also avoiding or minimizing injury to the intercostal neurovascular bundle, lungs and other internal structures. In addition, the chest tube must be well secured to the chest wall so that it cannot be accidently dislodged, and it must also be easily removable once the pneumo/hemothorax is absorbed.
Several techniques are currently used to insert a chest tube, each of which involves a relatively lengthy manual procedure that requires knowledge and experience. The most common technique involves surgical preparation and draping at the site of the tube insertion (usually at the nipple level-fifth intercostal space, anterior to the midaxillary line on the affected side), administering of local anesthesia to the insertion site, and making a 2-3 cm horizontal incision. A clamp is inserted through the incision and spread until a tract large enough to accept a finger is created. Next, the parietal pleura is punctured with the tip of a clamp, and the physician places a gloved finger into the incision to clear adhesions and to confirm the presence of a free pleural space locally. The proximal end of the chest tube is clamped and the tube is advanced into the pleural space. As the chest tube is inserted, it is directed posteriorly and superiorly. In this position, the chest tube will effectively clear the pleural space of both air and blood.
Once the chest tube is appropriately in place (determined by listening to air movement using a stethoscope), the tube is connected to an underwater-seal apparatus or to another one-way valve in order to clear air/blood from the pleural space. The tube is sutured to the skin, dressing is applied, and the tube is taped to the chest.
Insertion of a chest tube using this standard technique can require more than 15 minutes to accomplish by a physician and requires extensive medical training to be performed properly. Further, while performing the procedure, the physician must attend to the patient receiving the chest tube and thus is precluded from attending to other patients.
Various other specialized techniques are known, including the use of a rigid trocar (a sharp-pointed instrument equipped with a cannula); xe2x80x9cover-the-wirexe2x80x9d techniques (involving the insertion of a needle, attached to a syringe, through an incision and into the pleural cavity, and the introduction of a guide wire used to guide the insertion of progressively larger dilators or angioplasty ballons, and finally a chest tube); peel-away introducers for the insertion of mini-thoracostomy tubes in patients with spontaneous pneumothorax; and disposable laparoscopic trocar-cannulae.
U.S. Pat. No. 5,478,329 to Temamian teaches a xe2x80x9cTrocarless Rotational Entry Cannulaxe2x80x9d which can be used for gaining access to the peritoneal cavity for insertion of a laproscope. The Temamian cannula has screw threads on its outer surface and has a lumen extending throughout the entire length of the cannula. In use, an incision is first made and the cannula is turned into the patient, leaving access to the body cavity from the outside via the lumen. Since the cannula has an opening large enough for a laproscope to be inserted into the peritoneal cavity, a cylindrical piece of tissue is removed from the patient during insertion. The cannula remains inserted in the patient in its entirety while in use.
Each of the above-mentioned specialized techniques, excluding the use of a trocar, may result in fewer complications than standard techniques. Most also require that an incision be made to initiate the insertion (since an incision reduces the xe2x80x9csnugnessxe2x80x9d of the device with respect to the chest wall, an incision reduces the stability of the device which may cause the device to move, change the angle of penetration or result in an accidental disengagement of the device from the chest wall). However, all are lengthy and require an extensive training to perform. Such training is usually provided only to physicians. Since the Ternamian cannula remains inserted in the patient during use, its sharp tip in the vicinity of internal organs increases the possibility of injury resulting from its use. It would be desirable to have a method and apparatus for insertion of a chest tube which is simpler and can be performed more quickly and by medical support staff, rather than requiring the services of a highly trained physician or specialist.
The present invention is an improved device for gaining access to a body cavity for the purpose of inserting into the cavity a medical device, such as a chest tube. The device generally comprises a catheter and a cannula insertable into the catheter during an insertion procedure. The cannula has a cutting tip that extends beyond one end of the catheter. The cutting tip enables simple insertion of the device into the body without requiring substantial pushing force. Once the device is inserted in the body, the cannula is removed, leaving a path of entry into the body cavity, while removing the sharp cutting tip from the area to reduce the likelihood of injury to a patient in whom the device is inserted.
In a first embodiment, the present invention is a tube insertion device, comprising: a generally tubular catheter having a distal end and a proximal end; and a cannula having a cutting tip at a distal end, the cannula being insertable into the proximal end of the catheter during an insertion procedure so that the distal end of the cannula extends beyond the distal end of the catheter to provide the tube insertion device with a cutting tip. In a preferred embodiment, the cutting tip comprises a tapered, threaded section terminating in a point at the distal end of said cannula, and the catheter includes a threaded section along its outer diameter, so that when the cannula is inserted into the catheter, the threaded section of the catheter and the threaded section of the cutting tip coincide to form an essentially continuous threaded section along the tube insertion device.